the development of high temperature water-gas shift catalysts for ...

Chemeca 2011, Sydney, NSW, Australia
18−21 September, 2011
THE DEVELOPMENT OF HIGH TEMPERATURE WATER-GAS SHIFT
CATALYSTS FOR PRODUCTION OF HYDROGEN FROM SIMULATED COAL-
DERIVED SYNGAS
Y Sun a* , S S Hla b , G J Duffy a , A Cousins b , D French c , L Morpeth b , J H Edwards a
and D G Roberts b
Introduction
a
CSIRO Energy Technology, PO Box 330, Newcastle 2300, Australia
b
CSIRO Energy Technology, PO Box 883, Pullenvale, QLD 4069, Australia
c CSIRO Energy Technology, PO Box 52, North Ryde, NSW 1670 Australia
*Corresponding author. Tel.: +61 2 4960 6106; fax: +61 2 4960 6111
E-mail address: yanping.sun@csiro.au
Integrated Gasification Combined Cycle (IGCC) with CO 2 capture is one of the key clean coal technologies.
However, high capital and operating costs currently prevent widespread implementation of the technology. Novel
water-gas shift technology that integrates a high temperature water-gas shift (HT-WGS) catalyst with an efficient
and cost-effective membrane for in-situ separation of product H 2 or CO 2 to drive the equilibrium-limited WGS
reaction to the right (Eq. 1) has the benefit of potentially achieving total conversion of CO and reducing the costs
of CO 2 capture:
CO + H 2 O (g) ↔ H 2 + CO 2 ∆H° 25°C = − 41 kJ/mol (1)
It is more efficient to operate a catalytic membrane reactor (CMR) at high temperature because high temperature
results in faster reaction rates which lead to high H 2 yield. Furthermore, operation of a CMR at high temperature
could reduce the need for cooling the high temperature synthesis gas leaving a gasifier prior to shifting, thereby
conserving energy. However, no existing commercial WGS catalysts can be operated at temperatures greater than
450°C.
In the present work, three types of HT-WGS catalysts were designed and tested for the WGS reaction in the
temperature range 450 to 600°C and 1 atm in simulated coal-derived syngas. In addition, a variety of catalyst
characterisation studies was carried out in an attempt to clarify the reaction mechanism of the WGS reaction over
these catalysts. The results provide valuable insight into the activity and stability of these catalysts, which could
be applied to the design and development of novel, highly active and stable HT-WGS catalysts for use in WGS
membrane reactors.
HT-WGS catalyst design and formula
Cu and Fe were chosen as active metals in HT-WGS catalysts because Cu and Fe have good activity for the WGS
reaction at low and moderately high temperatures. However, they are prone to sintering at high temperatures and
Fe 2 O 3 tends to be over-reduced to FeO or Fe under HT-WGS reaction conditions, which is inactive for the WGS
reaction. Therefore, the major challenge in developing novel HT-WGS catalysts is to design a refractory oxide
which is able to stabilize Cu and Fe at temperatures greater than 500°C.
The redox oxide CeO 2 was chosen as the main catalyst support for the HT-WGS catalysts due to its high oxygen
storage capacity (OSC), high oxygen mobility and facile reducibility, which means that it can act as an oxidant to
participate in the WGS reaction. The introduction of La 2 O 3 , ZrO 2 or Al 2 O 3 into CeO 2 can improve its thermal
stability, oxygen storage capacity and increase metal dispersion, thus improving its catalytic activity (Kaspar et al
1999). In addition, oxides with a perovskite structure (ABO 3 ) are another alternative as catalyst support due to
their high stability, high redox property, and ability to control acid-base properties (Pena et al 2001). Hence,
mixed redox metal oxides and perovskite-like oxides were selected as catalyst supports for the novel Cu- and Fecontaining
catalysts. Based on the above rationale, a number of novel HT-WGS catalyst formulations were
designed and are listed in Table 1.
Table 1 The formula of HT-WGS catalysts

Yanping Sun et al, Chemeca 2011
She has attended numerous national and international conferences and published one US patent and 32 academic
and conference papers.
4